The Foo Fighters posted this photo of David Grohl and Cee Lo Green on their twitter page after the Foo Fighters and Cee Lo Green played Prince's "Darling Nikki" together. http://yfrog.com/gy4lj7j

GULF SHORES, Alabama -- The audience at the 2011 Hangout Music Festival got a big surprise about 4 p.m. today, when, without warning, organizers revealed that mainstage act Cee Lo Green would not be appearing -- and that the day's top act, the Foo Fighters, was going to fill in with an extra early set.

The organizer who made the announcement, some 20 minutes after Green's scheduled 3:30 start time, appeared to be festival founder Shaul Zislin. His remarks were brief and not entirely intelligible, so the reason behind the change-up was unclear. Among the phrases that could be clearly heard were "We had a problem," and "Cee Lo Green, forget you."

Audience reaction was muted, but cheers grew as the Foo Fighters walked onto the stage.

"Looks like we're playing two shows today," announced singer Dave Grohl. "Let's make this the fun one, what do you say?"

With that, the band launched into the '70s Alice Cooper hit "School's Out," followed by a Queen song.

Organizers were not immediately available for comment about the situation, but one thing was clear: The news did not trigger much of an exodus from the area in front of the Hangout Stage.

View full sizeThe Foo Fighters play a concert in this July 12, 2008, photo. The band helped Hangout Music Festival organizers cover Cee Lo Green's set Saturday, May 21, 2011. (AP Images for VH1/ Mark Davis)

About 25 minutes later, Green jumped on stage with the Foo Fighters sporting a tank top and sweat pants. Together they covered Prince's "Darling Nikki"

Green returned to the stage and performed for about 15 minutes. Green, and his all girl backup band played 5 songs, incudling "F-- You," more politely known as "Forget You" and "Crazy" from his old band Gnarls Barkley.

Angry Tweets reflected the crowds dismay at Green's late arrival and his short set list. Many using Green's "F--- You" phrase as a hashtag.

Green was also late to Coachella music festival April 18. He was booed by the crowd and only played five songs before organizers pulled the plug on his set.